关于than对称的一道题。。。

1.        In his eagerness to find a city worthy of Priam, the German archaeologist Schliemann cut through Troy and uncovered a civilization a thousand years older as was the city Homer’s heroes knew.

(A) older as was the city Homer’s heroes knew

(B) more ancient than the city known to Homer’s heroes

(C) older than was the city known to Homer’s heroes

(D) more ancient of a city than Homer’s heroes knew（B）

(E) older of a city than was the one known to Homer’s heroes

答案B里than两边一个是civilization,，一个是city，怎么对称？